1. Field of the Invention
The present invention relates to a semiconductor memory device with a high speed test function and, more particularly, to a semiconductor memory device which carries out a stress test, such as a burn-in test, of memory cells therein.
2. Description of the Prior Art
In general, since many process steps are required to fabricate a semiconductor device, failure causing factors are included in the semiconductor device fabricated thus. Burn-in test is used for detecting such failure causing factors, in particular, an infant morality.
For example, in a DRAM (Dynamic Random Access Memory) of semiconductor memory devices, a main memory region to a peripheral circuit region has the ratio of 80 to 20 and the ratio that the main memory region is occupied in the total dimension is very large. Herein, there are several methods for testing a failure of memory cells, one of which is a burn-in test that is to detect a reliability, in particular, to detect whether a failure is generated in a gate oxide or not by applying a high voltage to a word line.
In prior art, a high voltage of about 8 V has been applied to each of memory cells during burn-in test in the same manner as the normal operation of the memory device. Thus, in the prior memory device, a burn-in test is carried out by the procedure that any addresses are received through plural address buffers therein and then the memory cell corresponding to the addresses received thus is selected by means of a decoder.
For example, in case of one mega DRAM which is a x1 type that one data is inputted/outputted for one cycle and consists of four memory blocks, it has ten row/column addresses. Accordingly, an RAS(Row Address strobe) signal is applied and the row of the predetermined memory cell is selected through a row decoder receiving ten row addresses. Thus, two row addresses of ten row addresses are used as a block select address and provided to select one block of the four memory blocks.
However, since a burn-in test of the memory device should be carried out in the same method as the writing method of the normal operation, there is the problem that many times are necessary to carry out the burn-in test thereof.